1. Field of the Invention
The present invention relates to a data driver, an organic light emitting display device using the same, and more particularly, to a data driver to display an image with desired brightness and an organic light emitting display device using the same.
2. Description of Related Art
Various flat panel displays have recently been developed as alternatives to a relatively heavy and bulky cathode ray tube (CRT) display. The flat panel displays include liquid crystal display (LCD), field emission display (FED), plasma display panel (PDP), organic light emitting display device (OLED), and the like.
Among the flat panel displays, the organic light emitting display device can emit light by electron-hole recombination. The organic light emitting display device has advantages of relatively fast response time and relatively low power consumption. Generally, the organic light emitting display device employs a transistor provided in each pixel for supplying current corresponding to a data signal to a light emitting device, thereby causing the light emitting device to emit light.
FIG. 1 illustrates a conventional organic light emitting display device. The conventional organic light emitting display device includes a display region 30 including pixels 40 formed in a region defined by intersection of scan lines S1 to Sn and data lines D1 to Dm; a scan driver 10 to drive the scan lines S1 to Sn; a data driving part 20 to drive the data lines D1 to Dm; and a timing controller 50 to control the scan driver 10 and the data driving part 20. Each pixel 40 includes a transistor for supplying current to a light emitting device (not shown).
The timing controller 50 generates a data control signal DCS and a scan control signal SCS corresponding to an external synchronization signal. The data control signal DCS and the scan control signal SCS are supplied from the timing controller 50 to the data driving part 20 and the scan driver 10, respectively. Further, the timing controller 50 supplies external data to the data driving part 20.
The scan driver 10 receives the scan control signal SCS from the timing controller 50. The scan driver 10 generates scan signals on the basis of the scan control signal SCS and supplies the scan signals to the scan lines S1 to Sn.
The data driving part 20 receives the data control signal DCS from the timing controller 50. The data driving part 20 generates data signals on the basis of the data control signal DCS and supplies the data signals to the data lines D1 to Dm while synchronizing with the scan signals.
The display region 30 receives first voltage ELVDD and second voltage ELVSS from a power source, and supplies them to the pixels 40. When the first voltage ELVDD and the second voltage ELVSS are applied to the pixels 40, each pixel 40 controls and causes a current corresponding to the data signal to flow from a first voltage ELVDD power source line to a second voltage ELVSS power source line via the light emitting device, thereby emitting light corresponding to the data signal.
That is, in the conventional organic light emitting display device, each pixel 40 emits light with a predetermined brightness corresponding to the data signal, but cannot emit light with desired brightness because transistors provided in the respective pixels 40 are different in threshold voltage from each other. Further, in the conventional organic light emitting display device, there is no method of measuring and controlling the real current in each pixel 40 corresponding to the data signal.